In a move considered aggressive by US and European officials, Russia has sent at least 12 warships to patrol waters near its naval base in Tartous, Syria.

The deployment appears to be a warning to Israeli and Western officials against military intervention in Syria’s bloody civil war, which has now claimed the lives of over 80,000 people.

Russia’s increased presence in the region — which began raising eyebrows in the US three months ago — represents one of its largest sustained naval deployments since the Cold War, the Wall Street Journal reported on Thursday.

“It’s a show of force. It’s muscle flexing,” a top US official told the Journal.